1867 - 4b yellow, 1st issue, and 20c red brown, 2n

 1867 - 4b yellow, 1st issue, and 20c red brown, 2nd issue, from “ROMA 30 SET. 67' to Naples. The 20c was duly cancelled with the mute lozenge, while the 4b was not cancelled as it had become invalid from 21 September. The letter reached Naples on 1 October, the day the convention between the Papal States and the Kingdom of Italy came into force, but was nonetheless taxed 20c (handstamp “2') and the 4baj stamp was cancelled upon arrival with the red dotted numeral “19' to confirm its invalid use. Extremely rare and interesting. Certs. Chiavarello, Colla and Manzoni (Sassone 5A+18 - Euro -)